Default action is now Search instead of OPEN (winXP)

at one of winXP computer at my friend's place whenever he doubleclick any drive to get in , he instead find that "Search" is opened.

to get in drive he have to first right click and select "OPEN" then he can go in.

on righ click he finding following options :

--> Search
--> Explore
--> Open
--> Blah blah.

But instead it should be like
--> Open
--> Explore
--> Search
--> Blah blah

....
So basically I think we can somehow change it back to normal ie "Open" as default action of double click but from where ?
Its Windows XP ...